This invention relates to a method and materials to prevent bonding between metal parts exposed to corrosive gases at high temperatures. More particularly, the invention relates to interposing at least one layer of high melting, nonmetallic, micron sized particles between the mating surfaces of internal combustion engine or exhaust system components to prevent seize between them.
High temperatures and corrosive atmospheres are encountered by automotive internal combustion power plants and their exhaust trains. By the power plant is meant the engine block and power generating piston assemblies. By exhaust train is meant the engine manifold and the conduit components downstream thereof to the tailpipe. Components such as manifold oxygen exhaust sensors, catalytic converters, resonators and mufflers may reach temperatures as high as 1,000.degree. C. during engine operations. At such temperatures, adjacent metals tend to weld or sinter together. Moreover, gases such as water, sulfur oxides, and nitrogen oxides are formed by the combustion of air and petroleum based hydrocarbon fuels. The interaction of these hot gases with each other and metal surfaces may cause corrosion bonding. Herein, the tendency of adjacent metal surfaces to bond together by the combined effects of high temperature and a corrosive atmosphere is referred to as "seize." This invention relates to preventing seize between metal parts in general and automotive parts in particular. When seize occurs between parts in the engine or exhaust train of an automobile, it becomes difficult or impossible to separate them for repair or replacement. Attempts have been made to prevent seize between parts by coating them with a relatively inert metal such as silver. However, this method is expensive and unreliable at temperatures above about 800.degree. C. Another approach has been to coat parts with a mixture of high viscocity petroleum grease and aluminum, silver, or copper flake powder. However, this method is also expensive, and the parts once coated are messy and hard to handle. Moreover, the grease may be adversely affected at temperatures over 800.degree. C.